Currently, IPv6 is supported in various terminals, such as personal computers or portable devices, and IPv6 packets flow across networks. In addition, only IPv6 addresses are acquired as new global addresses in the future. Accordingly, the use of IPv6 across networks is expected to be further rapidly increased.
As one of the addresses used in IPv6, there is the link local address. The scope of the link local address is limited to within the same broadcast segment (within the same link). In general, a communication device is provided with a plurality of interfaces, such as physically different interfaces including a cable interface and a wireless interface, and a virtual interface used in a virtual local area network (VLAN) or the like. In any interface, the prefix of the link local address is the same as that of another interface. Accordingly, it is not possible to uniquely specify the broadcast segment, to which each interface belongs, with only the link local address. FIG. 15 is a diagram for explaining communication using a link local address. In FIG. 15, two links are connected to a communication device (node X). However, in both the links, the prefix is “fe80::/64”. Accordingly, since the communication device (node X) cannot distinguish the links from each other with only the link local address, it is not possible to determine which interface is to be used in order to communicate with a communication destination device.
Therefore, in the case of communication using a link local address, it is necessary to specify the interface used by the communication source device in the communication. In the specification (RFC4007) of the current IPv6, it is determined that the destination is specified by assigning the ID of the interface used in the communication to the link local address. In RFC4007 (Non-patent Document 1), the interface ID assigned to the link local address is expressed as “Zone ID”. Hereinafter, in this specification, the interface ID assigned to the link local address is expressed as “Zone ID”. In addition, in RFC3542 (Non-patent Document 2), how the Zone ID is transmitted as an argument of a library is defined. In RFC6874 (Non-patent Document 3), how to deal with problems that may occur when the Zone ID is included in the uniform resource identifier (URI) is described.
In addition, the following Patent Document 1 discloses that, when a network device is connected to the IPv6 network, a home gateway (HGW) builds a home IPv6 network by automatically generating a link local address using an interface ID (Zone ID) set in the network device in advance.